Aromatic polyamide films for transparent flexible substrates

Abstract

The present invention is directed toward transparent films prepared from soluble aromatic copolyamides with glass transition temperatures greater than 300 C. The copolyamides, which contain pendant carboxylic groups are solution cast into films using N,N-dimethylacetamide (DMAc), N-methyl-2-pyrrolidinone (NMP), or other polar solvents. The films are thermally cured at temperatures near the copolymer glass transition temperature. After curing, the polymer films display transmittances >80% from 400 to 750 nm, have coefficients of thermal expansion of less than 20 ppm, and are solvent resistant. The films are useful as flexible substrates for microelectronic devices.

Having thus described the invention, it is now claimed: 
     
       1. A polymer solution capable of being made into transparent films; wherein the polymer solution comprises an aromatic copolyamide that is soluble in polar aprotic solvents, is capable of being thermally crosslinked, and has one or more repeat units of general formula (I) and one or more repeat units of general formula (II), the general formulas (I) and (II) having the following structures: 
       
         
           
           
               
               
           
         
         wherein n=1 to 3; 
         wherein X and Y are molar ratios of the repeat units (I) and (II) and X is from 0.90 to 0.98 and Y is from 0.10 to 0.02, respectively; 
         wherein Ar 1  is selected from the group consisting of: 
       
       
         
           
           
               
               
           
         
         wherein p=1 to 4 and q=1 to 3, and wherein R 1 , R 2 , R 3 , R 4 , R 5  are selected from the group consisting of hydrogen, halogen, alkyl, substituted alkyl, nitro, cyano, thioalkyl, alkoxy, substituted alkoxy, aryl, or substituted aryl, alkyl ester and substituted alkyl esters, and combinations thereof, wherein G 1  is selected from the group consisting of a covalent bond; a CH 2  group; a C(CH 3 ) 2  group; a C(CF 3 ) 2  group; a C(CX 3 ) 2  group, wherein X is a halogen; a CO group; an O atom; a S atom; a SO 2  group; a Si (CH 3 ) 2  group; 9, 9-fluorene group; substituted 9, 9-fluorene; and an OZO group, wherein Z is an aryl group or substituted aryl group selected from the group consisting of a phenyl group, biphenyl group, perfluorobiphenyl group, 9, 9-bisphenylfluorene group, and substituted 9, 9-bisphenylfluorene; wherein when p is less than 4 or q is less than 3 the remaining positions on the aromatic ring are assumed by hydrogen atoms; and 
         wherein at least one of the Ar 1  groups in at least one of the repeat units (I) or at least one of the repeat units (II) is selected from the group consisting of: 
       
       
         
           
           
               
               
           
         
         wherein Ar 2  is selected from the group consisting of: 
       
       
         
           
           
               
               
           
         
         wherein p=1 to 4, wherein R 6 , R 7 , R 8  are selected from the group consisting of hydrogen, halogen, alkyl, substituted alkyl, nitro, cyano, thioalkyl, alkoxy, substituted alkoxy, substituted aryl, alkyl ester, and substituted alkyl esters, and combinations thereof, wherein G 2  is selected from the group consisting of a covalent bond; a CH 2  group; a C(CH 3 ) 2  group; a C(CF 3 ) 2  group; a C(CX 3 ) 2  group, wherein X is a halogen; a CO group; an O atom; a S atom; a SO 2  group; a Si (CH 3 ) 2  group; 9, 9-fluorene group; substituted 9, 9-fluorene; and an OZO group, wherein Z is a aryl group or substituted aryl group selected from the group consisting of a phenyl group, biphenyl group, perfluorobiphenyl group, 9, 9-bisphenylfluorene group, and substituted 9, 9-bisphenylfluorene; wherein when p is less than 4 the other positions on the aromatic ring are assumed by hydrogen atoms; and 
         wherein at least one of the Ar 2  groups in at least one of the repeat units (I) is selected from the group consisting of: 
       
       
         
           
           
               
               
           
         
         wherein Ar 3  is selected from the group consisting of: 
       
       
         
           
           
               
               
           
         
         wherein t=1 to 3, wherein R 9 , R 10 , R 11  are selected from the group consisting of hydrogen, halogen, alkyl, substituted alkyl, nitro, cyano, thioalkyl, alkoxy, substituted alkoxy, aryl, substituted aryl, alkyl ester, carboxyl, and substituted alkyl esters, and combinations thereof, wherein G 3  is selected from the group consisting of a covalent bond; a CH 2  group; a C(CH 3 ) 2  group; a C(CF 3 ) 2  group; a C(CX 3 ) 2  group, wherein X is a halogen; a CO group; an O atom; a S atom; a SO 2  group; a Si (CH 3 ) 2  group; 9, 9-fluorene group; substituted 9, 9-fluorene; and an OZO group, wherein Z is a aryl group or substituted aryl group selected from the group consisting of a phenyl group, biphenyl group, perfluorobiphenyl group, 9, 9-bisphenylfluorene group, and substituted 9, 9-bisphenylfluorene; wherein when t is less than 3, the remaining positions on the aromatic ring are assumed by hydrogen atoms; and 
         wherein at least one Ar 3  group in at least one of the repeat units (II) is selected from the group consisting of: 
       
       
         
           
           
               
               
           
         
       
     
     
       2. The polymer solution of  claim 1 , wherein the copolyamide contains more than one repeat units with structures (I) or (II), where Ar 1 , Ar 2 , and Ar 3  are the same or different in each repeat unit (I) and each repeat unit (II). 
     
     
       3. The polymer solution of  claim 1 , wherein the polymer solution is solution cast into a film that has a film transparency of >80% between 400 nm and 750 nm. 
     
     
       4. A transparent copolyamide film prepared by casting the polymer solution of  claim 1  and heating the resulting copolyamide film until it will no longer dissolve or swell in polar aprotic organic solvents. 
     
     
       5. The transparent copolyamide film of  claim 4 , wherein the transparent copolyamide film has a coefficient of thermal expansion that is less than approximately 20 ppm/° C. 
     
     
       6. The transparent copolyamide film of  claim 4 , wherein the transparent copolyamide film is heated at approximately 300° C. or higher for approximately 3 minutes or longer. 
     
     
       7. The transparent copolyamide film of  claim 4 , wherein the transparent copolyamide film has a transparency that is >80% between 400 nm and 750 nm. 
     
     
       8. The transparent copolyamide film of  claim 7 , wherein the transparent copolyamide film has a thickness of approximately 10 μm or more. 
     
     
       9. The transparent copolyamide film of  claim 7 , wherein the transparent copolyamide film is adhered to a substrate and wherein the transparent copolyamide film has a thickness that is greater than approximately 5 μm. 
     
     
       10. The transparent copolyamide film of  claim 9 , wherein the substrate is a glass film with a thickness greater than approximately 25 μm. 
     
     
       11. A transparent film formed from a polymer solution comprising an aromatic copolyamide that is soluble in polar aprotic solvents, is capable of being thermally crosslinked at approximately 300° C. or higher, and has one or more repeat units of general formula (I) and one or more repeat units of general formula (II), the general formulas (I) and (II) having the following structures: 
       
         
           
           
               
               
           
         
         wherein n=1 to 3; 
         wherein X and Y are molar ratios of the repeat units (I) and (II) and X is from 0.90 to 0.98 and Y is from 0.10 to 0.02, respectively; 
         wherein Ar 1  is selected from the group consisting of: 
       
       
         
           
           
               
               
           
         
         wherein p=1 to 4 and q=1 to 3, and wherein R 1 , R 2 , R 3 , R 4 , R 5  are selected from the group consisting of hydrogen, halogen, alkyl, substituted alkyl, nitro, cyano, thioalkyl, alkoxy, substituted alkoxy, aryl, or substituted aryl, alkyl ester and substituted alkyl esters, and combinations thereof, wherein G 1  is selected from the group consisting of a covalent bond; a CH 2  group; a C(CH 3 ) 2  group; a C(CF 3 ) 2  group; a C(CX 3 ) 2  group, wherein X is a halogen; a CO group; an O atom; a S atom; a SO 2  group; a Si (CH 3 ) 2  group; 9, 9-fluorene group; substituted 9, 9-fluorene; and an OZO group, wherein Z is an aryl group or substituted aryl group selected from the group consisting of a phenyl group, biphenyl group, perfluorobiphenyl group, 9, 9-bisphenylfluorene group, and substituted 9, 9-bisphenylfluorene; wherein when p is less than 4 or q is less than 3 the remaining positions on the aromatic ring are assumed by hydrogen atoms; and 
         wherein at least one of the Ar 1  groups in at least one of the repeat units (I) or at least one of the repeat units (II) is selected from the group consisting of: 
       
       
         
           
           
               
               
           
         
         wherein Ar 2  is selected from the group consisting of: 
       
       
         
           
           
               
               
           
         
         wherein p=1 to 4, wherein R 6 , R 7 , R 8  are selected from the group consisting of hydrogen, halogen, alkyl, substituted alkyl, nitro, cyano, thioalkyl, alkoxy, substituted alkoxy, substituted aryl, alkyl ester, and substituted alkyl esters, and combinations thereof, wherein G 2  is selected from the group consisting of a covalent bond; a CH 2  group; a C(CH 3 ) 2  group; a C(CF 3 ) 2  group; a C(CX 3 ) 2  group, wherein X is a halogen; a CO group; an O atom; a S atom; a SO 2  group; a Si (CH 3 ) 2  group; 9, 9-fluorene group; substituted 9, 9-fluorene; and an OZO group, wherein Z is a aryl group or substituted aryl group selected from the group consisting of a phenyl group, biphenyl group, perfluorobiphenyl group, 9, 9-bisphenylfluorene group, and substituted 9, 9-bisphenylfluorene; wherein when p is less than 4 the other positions on the aromatic ring are assumed by hydrogen atoms; and 
         wherein at least one of the Ar 2  groups in at least one of the repeat units (I) is selected from the group consisting of: 
       
       
         
           
           
               
               
           
         
         wherein Ar 3  is selected from the group consisting of: 
       
       
         
           
           
               
               
           
         
         wherein t=1 to 3, wherein R 9 , R 10 , R 11  are selected from the group consisting of hydrogen, halogen, alkyl, substituted alkyl, nitro, cyano, thioalkyl, alkoxy, substituted alkoxy, aryl, substituted aryl, alkyl ester, carboxyl, and substituted alkyl esters, and combinations thereof, wherein G 3  is selected from the group consisting of a covalent bond; a CH 2  group; a C(CH 3 ) 2  group; a C(CF 3 ) 2  group; a C(CX 3 ) 2  group, wherein X is a halogen; a CO group; an O atom; a S atom; a SO 2  group; a Si (CH 3 ) 2  group; 9, 9-fluorene group; substituted 9, 9-fluorene; and an OZO group, wherein Z is a aryl group or substituted aryl group selected from the group consisting of a phenyl group, biphenyl group, perfluorobiphenyl group, 9, 9-bisphenylfluorene group, and substituted 9, 9-bisphenylfluorene; wherein when t is less than 3, the remaining positions on the aromatic ring are assumed by hydrogen atoms; and 
         wherein at least one Ar 3  group in at least one of the repeat units (II) is selected from the group consisting of: 
       
       
         
           
           
               
               
           
         
       
     
     
       12. The transparent film of  claim 11 , wherein the copolyamide contains more than one repeat units with structures (I) or (II), where Ar 1 , Ar 2 , and Ar 3  are the same or different in each repeat unit (I) and each repeat unit (II). 
     
     
       13. The transparent film of  claim 11 , wherein the transparent film has a transparency of >80% between 400 nm and 750 nm. 
     
     
       14. The transparent film of  claim 11 , wherein the transparent film is heated until it will no longer dissolve or swell in polar aprotic organic solvents. 
     
     
       15. The transparent film of  claim 14 , wherein the transparent film is heated at approximately 300° C. or higher for approximately 3 minutes or longer. 
     
     
       16. The transparent film of  claim 14 , wherein the transparent film has a transparency >80% between 400 and 750 nm. 
     
     
       17. The transparent film of  claim 14 , wherein the transparent film has a thickness of approximately 10 μm or more. 
     
     
       18. The transparent film of  claim 14 , wherein the transparent film is adhered to a substrate and wherein the transparent film has a thickness that is greater than approximately 5 μm. 
     
     
       19. The transparent film of  claim 18 , wherein the substrate is a glass film with a thickness greater than approximately 25 μm. 
     
     
       20. The transparent film of  claim 14 , wherein the transparent film has an average coefficient of thermal expansion that is less than approximately 20 ppm/° C. between 100 and 200° C. 
     
     
       21. An aromatic copolyamide, wherein the aromatic copolyamide is soluble in polar aprotic solvents, is capable of being thermally crosslinked, has a glass transition temperature of at least 300° C., and has one or more repeat units of general formulas (I) and one or more repeat units of general formula (II), the general formulas (I) and (II) having the following structures: 
       
         
           
           
               
               
           
         
         wherein n=1 to 3; 
         wherein X and Y are molar ratios of the repeat units (I) and (II) and X is from 0.90 to 0.98 and Y is from 0.10 to 0.02, respectively; 
         wherein Ar 1  is selected from the group consisting of: 
       
       
         
           
           
               
               
           
         
         wherein p=1 to 4 and q=1 to 3, and wherein R 1 , R 2 , R 3 , R 4 , R 5  are selected from the group consisting of hydrogen, halogen, alkyl, substituted alkyl, nitro, cyano, thioalkyl, alkoxy, substituted alkoxy, aryl, or substituted aryl, alkyl ester and substituted alkyl esters, and combinations thereof, wherein G 1  is selected from the group consisting of a covalent bond; a CH 2  group; a C(CH 3 ) 2  group; a C(CF 3 ) 2  group; a C(CX 3 ) 2  group, wherein X is a halogen; a CO group; an O atom; a S atom; a SO 2  group; a Si (CH 3 ) 2  group; 9, 9-fluorene group; substituted 9, 9-fluorene; and an OZO group, wherein Z is an aryl group or substituted aryl group selected from the group consisting of a phenyl group, biphenyl group, perfluorobiphenyl group, 9, 9-bisphenylfluorene group, and substituted 9, 9-bisphenylfluorene; wherein when p is less than 4 or q is less than 3 the remaining positions on the aromatic ring are assumed by hydrogen atoms; and 
         wherein at least one of the Ar 1  groups in at least one of the repeat units (I) or at least one of the repeat units (II) is selected from the group consisting of: 
       
       
         
           
           
               
               
           
         
         wherein Ar 2  is selected from the group consisting of: 
       
       
         
           
           
               
               
           
         
         wherein p=1 to 4, wherein R 6 , R 7 , R 8  are selected from the group consisting of hydrogen, halogen, alkyl, substituted alkyl, nitro, cyano, thioalkyl, alkoxy, substituted alkoxy, substituted aryl, alkyl ester, and substituted alkyl esters, and combinations thereof, wherein G 2  is selected from the group consisting of a covalent bond; a CH 2  group; a C(CH 3 ) 2  group; a C(CF 3 ) 2  group; a C(CX 3 ) 2  group, wherein X is a halogen; a CO group; an O atom; a S atom; a SO 2  group; a Si (CH 3 ) 2  group; 9, 9-fluorene group; substituted 9, 9-fluorene; and an OZO group, wherein Z is a aryl group or substituted aryl group selected from the group consisting of a phenyl group, biphenyl group, perfluorobiphenyl group, 9, 9-bisphenylfluorene group, and substituted 9, 9-bisphenylfluorene; wherein when p is less than 4 the other positions on the aromatic ring are assumed by hydrogen atoms; and 
         wherein at least one of the Ar 2  groups in at least one of the repeat units (I) is selected from the group consisting of: 
       
       
         
           
           
               
               
           
         
         wherein Ar 3  is selected from the group consisting of: 
       
       
         
           
           
               
               
           
         
         wherein t=1 to 3, wherein R 9 , R 10 , R 11  are selected from the group consisting of hydrogen, halogen, alkyl, substituted alkyl, nitro, cyano, thioalkyl, alkoxy, substituted alkoxy, aryl, substituted aryl, alkyl ester, carboxyl, and substituted alkyl esters, and combinations thereof, wherein G 3  is selected from the group consisting of a covalent bond; a CH 2  group; a C(CH 3 ) 2  group; a C(CF 3 ) 2  group; a C(CX 3 ) 2  group, wherein X is a halogen; a CO group; an O atom; a S atom; a SO 2  group; a Si (CH 3 ) 2  group; 9, 9-fluorene group; substituted 9, 9-fluorene; and an OZO group, wherein Z is a aryl group or substituted aryl group selected from the group consisting of a phenyl group, biphenyl group, perfluorobiphenyl group, 9, 9-bisphenylfluorene group, and substituted 9, 9-bisphenylfluorene; wherein when t is less than 3, the remaining positions on the aromatic ring are assumed by hydrogen atoms; and 
         wherein at least one Ar 3  group in at least one of the repeat units (II) is selected from the group consisting of: 
       
       
         
           
           
               
               
           
         
       
     
     
       22. The aromatic copolyamide of  claim 21 , wherein the copolyamide contains more than one repeat units with structures (I) or (II), where Ar 1 , Ar 2 , and Ar 3  are the same or different in each repeat unit (I) and each repeat unit (II).